The present invention includes a device for and a method of-applying a coating to a material web such as, but not restricted to, a sheet of steel, aluminum, textile, paper, or film. An elongated feed nozzle is used to feed coating material under pressure. The pressure may be supplied by gravity or by a low pressure pump. The feed nozzle seals-up against either the web or a roll. The feed nozzle includes a fluid reservoir, a metering surface, end seals (end closures) and a back seal. The fluid reservoir, in conjunction with the end seals and the back seal, forms a cavity which contains the fluid as it is being fed through the feed nozzle. This avoids all the problems of having the coating in open trays. The present invention further provides a mechanism for rotating one nozzle out of the operating position and another nozzle into operating position, permitting a very quick change of coatings. With this arrangement, the nozzle that is off-line can be cleaned and prepared while the on-line nozzle is operating. The present invention also provides a support spring, which supports the nozzle and provides automatic position adjustment of the nozzle in response to the amount of force being exerted by the nozzle. The preferred embodiment also provides a nozzle contact angle adjustment mechanism, a mechanism to adjust the profile of the metering surface, a feed nozzle force sensor, a feed nozzle cleaning assembly, and an applicator roll cleaning assembly. A stiffener is used to make the metering surface rigid. The stiffener can be integral with the feed nozzle, or a separate stiffener can be attached to the feed nozzle. A preferred embodiment permits feed nozzle force control and contact surface angle control to be operated independently of one another, which cannot be achieved with die or slot coating. These technologies require precise control of clearances. The support spring, as the frame deflects and polymer covered rolls deform, permits the rotation of the feed nozzle to maintain a proper geometry, permitting increased control and a wider film thickness control range for a specific nozzle shape. The additional dynamic actuators of nozzle force and metering surface add new quality, speed and film thickness capability to web coating. Dynamic feed nozzle force control can be accomplished independent of reservoir cavity pressure and metering surface contact angle.
The feed nozzle and support frame can include a profile adjustment device to control the bending or profile across the feed nozzle bar, permitting variable coating thickness profiles or correcting variable thickness profiles across the web with this feed system. While the profile control of the housing or support is manual in the prototype described herein, the control can be done via hydraulic cylinders, stepper motors, pneumatic cylinders, manual linkages, etc. The profile control is not limited to the aforementioned but may be done in any manner that will permit controlled and repeatable flexing of the member.
Control of pressurized coating and coating build-up at ends of the feed bar is accomplished by means of an end seal in the feed nozzle bar. The end seal may have several different configurations.
The back seal may be made of any flexible blade compatible with the coating being applied that will seal and remain sealed against the surface being coated without causing damage. Examples of suitable materials include, but are not restricted to aluminum, steel, and plastic.